diff --git a/ChangeLog b/ChangeLog
index 2771f94544..d0cab08847 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+Tue Dec 18 04:58:22 2012  Koichi Sasada  <ko1@atdot.net>
+
+	* vm_trace.c (fill_id_and_klass): TracePoint#defined_class returns
+	  singleton class. `set_trace_func' passed attached class (which is
+	  attached/modified by singleton class) by 6th block parameter if it
+	  is singleton class. Previous behavior follows this spec.
+	  However, this method named `defined_class' should return singleton
+	  class directly because singleton methods are defined in singleton
+	  class. There are no compatible issue because TracePoint is introduced
+	  after 2.0.
+	  But compatiblity with `set_trace_func' is brokne. This means that
+	  you can not replace all `set_trace_func' code with TracePoint
+	  without consideration of this behavior.
+	  [Bug #7554]
+
+	* test/ruby/test_settracefunc.rb: change a test to catch up
+	  an above chagne.
+
 Tue Dec 18 03:03:10 2012  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* ext/psych/lib/psych/visitors/to_ruby.rb: speed up node mapping so
diff --git a/test/ruby/test_settracefunc.rb b/test/ruby/test_settracefunc.rb
index c6738494ae..0a30d04c02 100644
--- a/test/ruby/test_settracefunc.rb
+++ b/test/ruby/test_settracefunc.rb
@@ -418,12 +418,28 @@ class TestSetTraceFunc < Test::Unit::TestCase
         :nothing
       end
     }
+    _defined_class = lambda{|tp|
+      klass = tp.defined_class
+      begin
+        # If it is singleton method, then return original class
+        # to make compatible with set_trace_func().
+        # This is very ad-hoc hack. I hope I can make more clean test on it.
+        case klass.inspect
+        when /Class:TracePoint/; return TracePoint
+        when /Class:Exception/; return Exception
+        else klass
+          klass
+        end
+      rescue Exception => e
+        e
+      end if klass
+    }
 
     trace = nil
     begin
     eval <<-EOF.gsub(/^.*?: /, ""), nil, 'xyzzy'
     1: trace = TracePoint.trace(*trace_events){|tp|
-    2:   events << [tp.event, tp.lineno, tp.path, tp.defined_class, tp.method_id, tp.self, tp.binding.eval("_local_var"), _get_data.(tp)]
+    2:   events << [tp.event, tp.lineno, tp.path, _defined_class.(tp), tp.method_id, tp.self, tp.binding.eval("_local_var"), _get_data.(tp)]
     3: }
     4: 1.times{|;_local_var| _local_var = :inner
     5:   tap{}
diff --git a/vm_trace.c b/vm_trace.c
index 9b8ec40b33..ec5fe4f2dd 100644
--- a/vm_trace.c
+++ b/vm_trace.c
@@ -716,9 +716,6 @@ fill_id_and_klass(rb_trace_arg_t *trace_arg)
 	    if (RB_TYPE_P(trace_arg->klass, T_ICLASS)) {
 		trace_arg->klass = RBASIC(trace_arg->klass)->klass;
 	    }
-	    else if (FL_TEST(trace_arg->klass, FL_SINGLETON)) {
-		trace_arg->klass = rb_iv_get(trace_arg->klass, "__attached__");
-	    }
 	}
 	else {
 	    trace_arg->klass = Qnil;
@@ -838,7 +835,36 @@ tracepoint_attr_method_id(VALUE tpval)
 }
 
 /*
- * Return class or id from +:class+ event
+ * Return class or module the method being called.
+ *
+ *          class C; def foo; end; end
+ *	    trace = TracePoint.new(:call) do |tp|
+ *            tp.defined_class #=> C
+ *          end.enable do
+ *            C.new.foo
+ *          end
+ *
+ * If method is defined by a module, then returns that module.
+ *
+ *          module M; def foo; end; end
+ *          class C; include M; end;
+ *	    trace = TracePoint.new(:call) do |tp|
+ *            tp.defined_class #=> M
+ *          end.enable do
+ *            C.new.foo
+ *          end
+ *
+ * Note that TracePont#defined_class returns singleton class.
+ * 6th block parameter of `set_trace_func' passes original class
+ * of attached by singleton class. This is a difference between
+ * `set_trace_func' and TracePoint.
+ * 
+ *          class C; def self.foo; end; end
+ *	    trace = TracePoint.new(:call) do |tp|
+ *            tp.defined_class #=> #<Class:C>
+ *          end.enable do
+ *            C.foo
+ *          end
  */
 static VALUE
 tracepoint_attr_defined_class(VALUE tpval)